Editing a group after opening it results in error message

If you perform the following actions in order to edit a group:

1. Open a group
2. Select Edit form the menu behind the name of the group
3. Edit settings
4. Click on submit

the following contradictory messages appears:

Success Group Edited

Not Found. The specified resource was not found or you do not have permission to access it.

The settings have been edited and the error message can be ignored.